Fig 1. Simulation of an RCT with 30 patients with MDD randomized to antidepressants or placebo with a mean difference between groups of 2 points on the HAMD-17.

Plotting the observed outcomes of both the antidepressant and placebo group shows variation and overlap in the outcomes in the two groups (a). Observing only the variation in the outcomes in the antidepressant group, while ignoring the variation in the placebo group, and ranking patients according to their outcome can encourage the assumption that the effect differs between individuals (b). Dichotomizing the outcomes based on arbitrary thresholds and the subsequent categorizing of patients as “responders” and “non-responders” can accentuate the perception of individual differences in treatment response and tempt into interpreting those as stable characteristics of the individual patient (c).